CU Boulder physicists automate plasma alignment for next-generation accelerators

Kirsten Apodaca — Mon, 12 Jan 2026 16:54:12 +0000

CU Boulder physicists automate plasma alignment for next-generation accelerators Kirsten Apodaca Mon, 01/12/2026 - 09:54

Kirsten Apodaca

Particle accelerators, like the Large Hadron Collider near Geneva, Switzerland, allow scientists to study the most fundamental particles, but they operate on a massive scale. The tunnel that houses the collider is about 12 feet wide and stretches in a loop over 16 miles long.

The sheer size of these colliders means experiments are expensive to run and have to be coordinated among large collaborations of scientists. But imagine if we could shrink these accelerators, making them available in smaller labs worldwide.

One approach to making smaller, more powerful particle accelerators is plasma wakefield acceleration. Traditional accelerators use metallic structures to create an electric field which increases the speed and energy of the particle beam. Magnetic fields then guide the beam in the right direction. In plasma wakefield acceleration, a special laser-ionized plasma source (an energized gas, the fourth state of matter) accelerates particles which has the potential to make accelerators much more compact and thousands of times more powerful.

In a recent study, a team of physicists at CU Boulder demonstrated the ability to align a laser-ionized plasma source with the electron beam in an ultra-precise and automated way, paving the way for future developments in making plasma wakefield accelerators a reality.

The plasma advantage

Valentina Lee during shift at FACET-II. (Image credit: SLAC/FACET-II)

The plasma source has a distinct advantage because it can handle electric fields much stronger than traditional accelerators, and it’s remarkably compact, says Valentina Lee, a physics graduate student and first-author on the team’s new paper. “Among the various types, the laser-ionized plasma source is the most appealing because it can be shaped in ways other sources cannot,” Lee adds.

“Using a laser to generate the plasma gives us total control over the three-dimensional shape of the plasma, which can be used to preserve the quality of the electron beam during acceleration,” says Lee. “This opens to the door to accelerating positrons (anti-electrons), in the future.”

The plasma accelerator designed by the group at CU measures only 40 centimeters long, about the length of a standard laptop screen. Yet, it provides as much energy to the electron beam as the 1-kilometer long conventional accelerator at SLAC National Accelerator Laboratory, where the Litos group's experiments take place.

If plasma accelerators become practical, they could bring the power of large-scale accelerators to smaller research facilities, like university labs.

Precision alignment

Using one of the highest-powered lasers on campus in the Litos group’s lab, the team verified the optics for the plasma source before running the experiment with the electron beam at FACET-II, the Facility for Advanced Accelerator Experimental Tests at the SLAC National Accelerator Laboratory in California.

Experiment time at the national accelerator lab is limited as research groups bid for slots on the schedule. Running an experiment at a facility like SLAC involves a lot of upfront planning and coordination.

“There are only so many months of beam time per year, and only so many of those hours are available to different users for their experiments,” explains Michael Litos, associate professor of physics.

For Lee, an experiment like this was something she had always hoped for. She had known she wanted to be a physicist since she was 8 years old, after children’s books sparked her interest. When choosing a research field, Lee wrote out what she liked. At the top of the list? Electromagnetics and lasers – giant lasers. So, when she found that plasma wakefield acceleration combined giant lasers with accelerating electrons, she was set.

Lee traveled back and forth to SLAC during her research, often spending two weeks at a time “running shift” on site. “At SLAC, a shift runs about 16 hours, then you go home for 8 hours to rest. Even though 16 hours sounds like a long time, originally it was taking us 12 hours just to set up the experiment, then we had 4 hours to actually do the plasma wakefield research,” said Lee.

Realizing more time was needed for the experiment, Lee teamed up with former Litos group graduate student Robert Ariniello, who at the time was a project scientist at SLAC. Together, they developed a process to automate the alignment, saving about 10 hours of setup time.

Valentina Lee and Robert Ariniello work on the plasma wakefield acceleration experiment at FACET-II. (Image credit: SLAC/FACET-II)

Positioning the plasma source and electron beam requires ultra-precise work. “We’re aligning a large-scale electron beam from one kilometer away with a laser from 40 meters away, and they have to be aligned with better than 10 micron precision. That’s about a tenth of the width of a human hair,” says Lee.

Lee explains that their novel alignment technique relies on analyzing the plasma afterglow light at two longitudinal positions as they scan the plasma column across the electron beam. “Plasma always glows a little but when it’s really bright then you know you have the perfect alignment,” she says.

It worked.

Seeing a working plasma wakefield accelerator for the first time was awe-inspiring for Lee. “I’ve been working in this field for seven years. We’ve talked about it and run simulations. To see it live for the first time was incredible,” she adds.

“Over the last year and a half, we’ve started seeing the high impact results that we’ve been working toward for most of a decade,” explains Litos. “This was an awesome experimental accomplishment which enabled the heart of Valentina’s thesis.”

With these results, Lee is finishing two more papers and will soon be writing her thesis.

The group’s research will help open doors to accelerating positrons, one of the key challenges in plasma wakefield acceleration. The alignment will have to be even more precise, but with Lee’s alignment technique, the team thinks it’s possible.

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Valentina Lee and Robert Ariniello work on the plasma wakefield acceleration experiment at FACET-II. (Image credit: SLAC/FACET-II)

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New materials, old physics—the science behind how your winter jacket keeps you warm

Kirsten Apodaca — Sun, 11 Jan 2026 17:24:36 +0000

New materials, old physics—the science behind how your winter jacket keeps you warm Kirsten Apodaca Sun, 01/11/2026 - 10:24

Winter jackets may seem simple, but sophisticated engineering allows them to keep body heat locked in while staying breathable enough to let out sweat. Read from CU experts Longji Cui, assistant professor in mechanical engineering, and Wan Xiong, physics graduate student, on The Conversation.

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If at first you don’t succeed: Outstanding grad’s perseverance pays off

Kirsten Apodaca — Tue, 23 Dec 2025 14:59:00 +0000

If at first you don’t succeed: Outstanding grad’s perseverance pays off Kirsten Apodaca Tue, 12/23/2025 - 07:59

Kirsten Apodaca

Hero Trent

Failing Calculus 1 during her first semester wasn’t exactly how Hero Trent hoped to start her college career at CU Boulder. But she faced the challenge head on, and now she’s seeing the results of her hard work and determination.

This fall, she’s not only graduating with her degree in engineering physics — Trent was also named the Outstanding Graduate in Engineering Physics, selected as a Quantum Scholar, completed a research project on fiber optic phase noise stabilization, and landed a job as an optical engineer at Quantinuum.

A rocky start

Trent was always interested in engineering but wasn’t sure about the specific field she wanted to pursue. “I took college classes in high school because I really loved learning, but I didn’t know exactly what I wanted to do at the time,” said Trent.

She completed an Associate of Science degree at Aims Community College in Greeley, Colorado. When she transferred to CU Boulder, she considered aerospace or environmental engineering. Still undecided, she started in exploratory studies.

“My first semester at CU Boulder, I took Calculus 1 and totally bombed it. I had never failed a class before – it was heart-wrenching,” she said. Trent knew she had to learn calculus if she wanted to do anything engineering-related.

“I forced myself to like it and spent 10 hours a day studying calculus over winter break” she said.

Determined, she took Calculus 1 again in the spring and earned an A. With a newfound love for math, Trent became a learning assistant for the course the following semester and started tutoring other students.

She also looked for a major where she could apply math. “I had always been interested in physics but thought I couldn’t handle it because of the rigorous math,” said Trent. “But I kept hearing that physics is basically applied calculus, so I decided to take my first physics class.”

Her academic advisor suggested the engineering physics major might be a good fit, combining her interests in engineering and physics. She went for it and discovered her passion along the way.

Quantum Scholars provides connections

Fast forward to spring 2024, Trent first heard about the Quantum Scholars program from Keith Molenaar, dean of engineering, at a Donuts with the Dean event. “He asked what my major was and then asked if I was part of Quantum Scholars,” said Trent.

Another nudge came when her history and philosophy of physics professor, Mike Ritzwoller, recommended that she apply.

The Quantum Scholars program helps undergraduates learn more about the quantum field and industry, provides professional development opportunities and community, and offers scholarships supported by alumni, industry and external partners.

She took their advice, applied, and joined Quantum Scholars in fall 2024. Ritzwoller, who co-founded Quantum Scholars with Molenaar, said he was “truly delighted” when she was selected.

Trent received a Jennifer Turner-Valle Quantum scholarship for her participation in Quantum Scholars, in honor of the late Dr. Turner-Valle, an engineering physics alumna.

While the scholarship helped, Trent still had to work while she was attending school. “For a while, I was working at Starbucks from 4 a.m. until noon and then I’d come to class after. I just had to accept that I was going to be busy,” she said.

Ritzwoller was impressed that she was working full time while also carrying a full academic load. “Even with those demands, she was an outstanding student,” he said.

Taking full advantage of what Quantum Scholars had to offer, Trent attended talks by leading quantum scientists and industry leaders, joined Women of Quantum meetings, and toured local quantum companies.

A research opportunity

For her engineering physics major, Trent took an introduction to electrical engineering class in fall 2024, taught by Professor Scott Diddams. That class opened the door to a research position.

“Hero immediately stood out as one of the most inquisitive, focused, and thoughtful students in the class,” said Diddams. “When she asked about a research position in my group, I didn’t hesitate to welcome her.”

Her research project focused on transmitting highly stable optical and millimeter wave signals through fiber. This research plays an important role in improving long-distance communication and precision timing systems used in modern technologies.

Trent explains, “as frequencies of light travel through optical fiber, different changes in pressure and temperature, or external effects, change the phase of the light. So, I build systems to stabilize it.”

This has been done for a single wavelength of light, but Diddams noted, “our research on generating and distributing millimeter waves requires sending two wavelengths through the same fiber.” He praised Trent’s “persistence and ingenuity” in testing several solutions before arriving at the best approach.

The project gave her hands on experience with lasers, fiber optics, electronics, control systems, and measuring phase fluctuations — all of which will be useful as she enters the quantum industry.

Perseverance and connection

It was a long journey that involved a lot of failure and picking myself back up, but I think I’ve found my passion, and I’m so glad I persevered."

As she reflects on her journey, Trent says the most important lessons she learned are perseverance and connection. And graduating from college represents her hard work paying off.

Trent was named Outstanding Graduate in Engineering Physics at the Department of Physics Recognition Ceremony, in recognition of her academic achievement and research experience.

“I wanted to give up regularly, but this represents that I can put my mind to something and follow through with it,” she said.

For future students, Trent recommends getting involved in a project or a relevant job outside of the classroom and stresses the importance for both graduate school and industry. “Your degree is your ticket to have a seat at the table, but you need to prove that you can actually do things.”

What’s next?

Trent has certainly proven herself. Connections she made through Quantum Scholars and her research project in the Diddams lab helped land her a job as an optical engineer at Quantinuum. She starts in January.

“It was a long journey that involved a lot of failure and picking myself back up, but I think I’ve found my passion, and I’m so glad I persevered,” she said. “I think everybody can do this if they choose to.”

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Team of NIST and CU Boulder physicists achieve new levels of control over molecules

Kirsten Apodaca — Mon, 22 Dec 2025 15:29:09 +0000

Team of NIST and CU Boulder physicists achieve new levels of control over molecules Kirsten Apodaca Mon, 12/22/2025 - 08:29

Physicists from NIST, including CU Boulder physics graduate students and CU PREP researchers, used laser-based techniques to employ a “helper” calcium atom and control a calcium hydride molecule nearly perfectly. Their results were recently published in Physical Review Letters.

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Physicist Jun Ye named to Quantum 100 list

Kirsten Apodaca — Thu, 18 Dec 2025 20:18:24 +0000

Physicist Jun Ye named to Quantum 100 list Kirsten Apodaca Thu, 12/18/2025 - 13:18

This week, UNESCO named Jun Ye, professor adjoint of physics and fellow of JILA and NIST, to its Quantum 100 list—a catalogue of some of the top leaders around the world in the rapidly growing field of quantum science.

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Professor Gang Cao awarded Research & Innovation seed grant for quantum transport and orbitronics

Kirsten Apodaca — Mon, 15 Dec 2025 20:44:24 +0000

Professor Gang Cao awarded Research & Innovation seed grant for quantum transport and orbitronics Kirsten Apodaca Mon, 12/15/2025 - 13:44

Professor Gang Cao has been awarded a seed grant from the Research & Innovation Office for his project titled "Chiral Orbital Currents: Engineering a New Platform for Quantum Transport and Orbitronics."

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New window insulation blocks heat, but not your view

Kirsten Apodaca — Thu, 11 Dec 2025 20:08:52 +0000

New window insulation blocks heat, but not your view Kirsten Apodaca Thu, 12/11/2025 - 13:08

Professor Ivan Smlayukh and his research group have developed a new material that is completely transparent but so good at blocking heat that you can use it to hold a flame in the palm of your hand. Their results were recently published in Science.

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Ruijian Wang earns undergrad research award for quantum optics and photonics

Kirsten Apodaca — Thu, 11 Dec 2025 13:28:45 +0000

Ruijian Wang earns undergrad research award for quantum optics and photonics Kirsten Apodaca Thu, 12/11/2025 - 06:28

Kirsten Apodaca

Physics senior Ruijian Wang has been awarded the Fall 2025 Stephen Halley White Undergraduate Research Award from the Department of Physics for his outstanding research in quantum optics and integrated photonics. The award is one of the top honors for graduating physics students at CU Boulder.

Established in 2013 by alumnus Dr. Stephen White (Phys’63), the award recognizes exceptional undergraduate research projects. During his undergraduate studies at CU Boulder, Dr. White held several research positions which made an impact on his career and led him to create this award.

A passion for physics

Wang said his interest in physics stemmed from a fascination with math, and how scientists can use a few elegant equations to describe the fundamental physical principles of our universe. He spent several years studying physics, math and music in China before continuing his studies in the United States.

He pursued his interest in Atomic, Molecular, and Optical (AMO) physics through research positions at Yale University and at MIT. As the first undergraduate student to work in Prof. Charles Brown's lab at Yale University, he designed and improved PID feedback control circuits for advanced quantum simulation experiments with quasicrystals. Later, as a visiting student at MIT’s physics department from 2023 to 2024, he worked with Prof. Ronald Fernando Garcia Ruiz and led the design, implementation, and optimization of an off-center rotating Ablation Ion Source for laser spectroscopy experiments.

After these experiences, Wang considered where to finish his bachelor’s degree, and Boulder was strongly recommended as a top choice.

Squeezed light on a chip

After transferring to CU Boulder, Wang started looking for a research group where he could enhance his hands-on skills with optics.

“I was very interested in Professor Scott Diddams’ leading work in frequency comb and quantum metrology, so I stopped by his office and asked for one minute to introduce myself. He said he had five minutes to talk before his next meeting,” said Wang. Nothing like a time crunch to make a good first impression – Wang quickly explained his interests and to his surprise, Diddams said he might have an opening on a new project.

His project in quantum optics and integrated photonics involved making a special quantum state of light, called a squeezed state, on a tiny photonic chip about half the size of a penny. This special state reduces uncertainty in one physical quadrature of a quantum system and is key to improving precision measurements and quantum metrology.

Wang suddenly had a lot of studying to do. At first, they didn’t have their own experimental table, so he began pouring over research papers on the topic. He and Diddams started building the experiment setup from an empty table and Wang said that experience gave him extensive training, both in designing and setting up the experiment and in purchasing and working with vendors.

“One of the most unique things I learned was not just the individual experimental techniques, but how to plan and execute a project in its entirety,” said Wang. He noted that the real-world experience combined with weekly collaboration review meetings have set him up well for his future research career.

“Ruijian is an exceptional undergraduate researcher with amazing drive and curiosity-driven motivation for learning,” said Diddams, Wang’s research advisor and professor of electrical, computer and energy engineering and physics. “Usually, the generation of squeezed light requires a full table of equipment, but Ruijian is showing how to do that using a small photonic chip that could ultimately fit on the tip of your finger.”

This experiment is the “first step towards a robust and scalable approach of on-chip squeezed-light sensors for a new class of integrated photonics sensors,” Wang described in his honors thesis.

Earning top honors

Wang received a summa cum laude designation from the College of Arts & Sciences Honors Program for writing and defending his undergraduate thesis. The Physics Honors Council Representatives then selected him to receive the Stephen Halley White Undergraduate Research Award.

Jun Ye, professor adjoint of physics and JILA fellow, served as the Physics Honors Council Representative on Wang’s defense. “I was very impressed with the scientific knowledge and technical depth that Ruijian demonstrated through his written thesis and verbal presentation,” said Ye.

Upon earning the research award, Wang said he was proud to receive recognition from the Honors Council Representatives and the Department of Physics.

“It was great to hear the faculty who served on my defense were interested in what we’re doing in the lab, both the science and application aspects. It was nice recognition,” said Wang. “I really appreciate the honor and it’s good encouragement for the future.”

What’s next?

After graduating this fall, Wang plans to continue working in Diddams’ lab as a researcher. As the first college student in his family, he’s currently applying for graduate school, planning to pursue a Ph.D. in physics next fall. He believes the most important aspect of higher education was that it gave him the opportunity to explore different career paths.

Wang also earned the Jennifer Turner-Valle Scholars Fellowship and an SPIE Fellowship from CU’s Quantum Scholars program. He said the program gave him great insight into the quantum industry, and he wants to continue conducting research to develop quantum technologies for real-world applications.

“As a part of the quantum community, I want to help develop the next generation of AMO techniques for both fundamental physics exploration and impactful applications outside physics labs,” said Wang.

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STEM Together Symposium 2025 brings leaders to shape STEM action

Kirsten Apodaca — Mon, 08 Dec 2025 18:46:55 +0000

STEM Together Symposium 2025 brings leaders to shape STEM action Kirsten Apodaca Mon, 12/08/2025 - 11:46

Hundreds of educators, students, scientists, policymakers, industry partners and community leaders gathered in November for STEM Together 2025: The STEM Education Action Symposium. Led by the Center for STEM Learning (CSL), the event was designed to advance collective action in STEM education and workforce development within Colorado’s strong innovative ecosystem.

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LASP instruments selected by NASA for Artemis IV mission

Kirsten Apodaca — Fri, 05 Dec 2025 16:00:21 +0000

LASP instruments selected by NASA for Artemis IV mission Kirsten Apodaca Fri, 12/05/2025 - 09:00

NASA has announced that instruments designed and built by researchers at the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder have been selected for development for the Artemis IV mission, due to launch in 2028. Xu Wang, senior researcher at LASP at lecturer of physics, serves as principal investigator of the proposal, dubbed DUSTER (Dust and plaSma environmenT survEyoR).

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Newsletter

CU Boulder physicists automate plasma alignment for next-generation accelerators

The plasma advantage

Precision alignment

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New materials, old physics—the science behind how your winter jacket keeps you warm

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If at first you don’t succeed: Outstanding grad’s perseverance pays off

A rocky start

Quantum Scholars provides connections

A research opportunity

Perseverance and connection

What’s next?

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Team of NIST and CU Boulder physicists achieve new levels of control over molecules

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Physicist Jun Ye named to Quantum 100 list

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Professor Gang Cao awarded Research & Innovation seed grant for quantum transport and orbitronics

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New window insulation blocks heat, but not your view

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Ruijian Wang earns undergrad research award for quantum optics and photonics

A passion for physics

Squeezed light on a chip

Earning top honors

What’s next?

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STEM Together Symposium 2025 brings leaders to shape STEM action

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LASP instruments selected by NASA for Artemis IV mission

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